Messages in this thread | | | Date | Sat, 09 Jun 2007 16:23:27 -0400 | From | Jeff Garzik <> | Subject | Re: [PATCH 2/3] [CRYPTO] Add optimized SHA-1 implementation for i486+ |
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Matt Mackall wrote: > On Fri, Jun 08, 2007 at 05:42:53PM -0400, Benjamin Gilbert wrote: >> Add x86-optimized implementation of the SHA-1 hash function, taken from >> Nettle under the LGPL. This code will be enabled on kernels compiled for >> 486es or better; kernels which support 386es will use the generic >> implementation (since we need BSWAP). >> >> We disable building lib/sha1.o when an optimized implementation is >> available, as the library link order for x86 (and x86_64) would otherwise >> ignore the optimized version. The existing optimized implementation for ARM >> does not do this; the library link order for that architecture appears to >> favor the arch/arm/ version automatically. I've left this situation alone >> since I'm not familiar with the ARM code, but a !ARM condition could be >> added to CONFIG_SHA1_GENERIC if it makes sense. >> >> The code has been tested with tcrypt and the NIST test vectors. > > Have you benchmarked this against lib/sha1.c? Please post the results. > Until then, I'm frankly skeptical that your unrolled version is faster > because when I introduced lib/sha1.c the rolled version therein won by > a significant margin and had 1/10th the cache footprint.
Yes. And it also depends on the CPU as well. Testing on a server-class x86 CPU (often with bigger L2, and perhaps even L1, cache) will produce different result than from popular but less-capable "value" CPUs.
Jeff
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